When it comes to generating PR buzz, these seven companies have shown that they know how to execute a stunt with a message that's moving, outrageous or just darn cute and generate some serious press coverage. Here are seven standout recent campaigns that could inspire you to shape your startups' publicity to result in significant buzz:

1. Chipotle's "Scarecrow" tackles sustainability.

Chipotle has done an excellent job differentiating itself from its fast-food brethren by highlighting its commitment to sustainable, hormone-free fare. But the company's methods of publicizing its value proposition are even more impressive. "The Scarecrow," released on Sept. 11, is the second cartoon-like video installment for Chipotle, in which the company highlights issues with factory farming through a somber narrative with a happy ending. ("Back to the Start" appeared two years earlier.)

The video is beautifully done and the company's multifaceted campaign included online games and sparked quite a discussion on social media. While reactions to the campaign were mixed, Chipotle is a prime example of a company that understands the value of starting, and being at the center of, a public dialogue.

2. Uber gets cuddly.

Nothing screams added value quite like offering up something warm and cuddly to snuggle with, which is exactly what Uber did with its "I Can Has Uberkittens" campaign on Oct. 29. Uber combined philanthropy, cute animals and social media trends to create the ultimate PR trifecta with a collaboration with Cheezburger. For the price of the typical bottomless brunch, Uber users in select cities could order fluffy, adoptable kittens to their doorsteps. Uber then donated all proceeds to local animal shelters. (You may say awww now.) This is just one of many examples of Uber's infamous PR stunts, and the organization is wise in capitalizing on unofficial holidays to garner widespread media attention.

3. Virgin America releases a #VXSafetyDance video.

The airline Virgin America is known for its attention to detail, but changing up one of the more mundane aspects of flying landed the company on an entirely different level. Its on-point safety video, released on Oct. 29, not only made its flights more pleasant. The video achieved viral status, with more 9.6 million times views on YouTube alone. This campaign is proof that the payoff is huge for companies that are willing to challenge the status quo in the name of customer satisfaction.

4. The Walking Dead invades NYC with zombie actors.

Movie and television show producers have jumped on the bandwagon of live stunts to generate excitement for upcoming releases to the delight of PR professionals and pretty much every other person not involved in the stunts themselves. For the creators of a show like AMC's The Walking Dead, hiring actors dressed as zombies on Feb. 5 to scare the pants off people was a no-brainer (pun intended). Thanks to sharing on social media and YouTube, a perfectly outrageous stunt like this could make your startup's brand go viral before you can say "BLERGAJARAGG!!!" (zombie speak for "Please like our brand on Facebook.").

5. Coca-Cola shows the love on Valentine's Day.

Coca-Cola is an iconic example of a company that stays true to its brand voice. No matter how diverse Coke's publicity efforts have been, it always returns to its core objective: spreading happiness and optimism. Coke shared the love on Valentine's Day by installing a hidden machine that only revealed itself (with the help of a screen projection) when couples strolled by. The two people are asked their names and granted a personalized Coke can (real!) as a keepsake. (This reworked a 2012 happiness machine for couples, Adweek noted.) True to its mission, Coca-Cola's video of the experiential campaign emphasizes the delight on the faces of couples throughout the stunt.

6. Zady issues a Wall Street Journal call to action

PR stunts aren't limited to established companies with million-dollar advertising budgets. The co-founders of the startup Zady took out a Wall Street Journal ad on April 9 just eight months or so after the launch of its sustainable-fashion ecommerce site. Zady's simple yet elegant call to action (taking a stand against "fast fashion") did an excellent job of communicating its mission statement and brand voice in a bold way in the already crowded e-commerce space. It sounded the alarm about "apparel produced inexpensively to keep up with fast-changing runway trends at low cost" and noted that "this manufacturing is harmful for the environment, for workers who are paid in pennies overseas." Not every startup can afford a full-page ad in a major news publication, but entrepreneurs can take a pointer from Zady’s example: Launch boldly, be strategic and amplify.

7. Morton's Steakhouse takes customer service to a new level.

Hey @Mortons - can you meet me at newark airport with a porterhouse when I land in two hours? K, thanks. :)

In lists of firms with social media savvy, Morton's Steakhouse might not be the first company that comes to mind. Known for its customer service, Morton's certainly delivered after taking advantage of a late-night serendipitous PR opportunity. Social media entrepreneur (and Morton's regular) Peter Shankman mentioned on Twitter on Aug. 17, 2011, that he would love a Morton's steak upon landing at Newark Airport. And Morton's delivered -- literally. When Shankman touched down in Newark, N.J., a tuxedo-clad Morton's delivery person was waiting for Shankman in the baggage claim area. The nearest Morton's is more than 23 miles away.

Which PR win is your favorite on the list? What others would you add? Tell us about your clever stunt?